Functional Ionic Liquids Catalyzed the Esterification of Ricinoleic Acid with Methanol to Prepare Biodiesel: Optimization by Response Surface Methodology

Abstract

RA]. Due to the presence of a hydroxyl group of RA, castor methyl ester has many better properties (for example, a high viscosity and a low viscosity index) than the biodiesel from other vegetable oils, such as, lubricity and high flash point, which make it attractive to be used in alcohol-diesel fuel blends [6,7].In the conventional methods for biodiesel preparation, the transesterification of oils and esterification of free fatty acids with alcohols were often used and catalyzed by basic (NaOCH 3 , KOCH 3 , NaOH, KOH) [8-10] or acid catalysts (H 2 SO 4 or heteropolyacid) [11,12]. Among these catalysts, basic catalysts (NaOH, KOH, NaOCH 3 ) are preferred to acid catalysts because of their high reactivity and fast reaction rates [13]. However, alkaline transesterification reactions of oils have some disadvantages, for examples, the presence of free fatty acids or water in the oils can form soap as well as mono-and di-acylglycerides, which can be an obstacle to the separation of the biodiesel from glycerin and reduce the yield and formation rate of biodiesel [14]. Therefore, in order to avoid these problems, more efficient and green catalysts and methods to prepare biodiesel have attracted much attention [15][16][17][18][19][20].Ionic liquids (IL), as novel environmental friendly catalysts, due to non-volatile, thermal stability, and easy separation, have been used as green solvents and catalysts in many reactions [15,[20][21][22][23][24][25]. In this work, IL were used as catalysts and RA was used as acyl donor for biodiesel preparation. Compared with those previous reports using castor oil as acyl donor [9,15], biodiesel preparation can be improved by the esterification of RA with methanol using IL as catalyst. The effect of different functional IL on the esterification were compared with the conventional catalysts. And the effects of reaction variables (reaction time, reaction temperature, IL load, and the ratio of reaction Abstract An efficient route to preparing biodiesel by the esterification of ricinoleic acid (RA) with methanol was investigated in the work. Six kinds of functional ionic liquids (IL) were selected as catalysts. The effects of reaction variables (reaction time, temperature, IL load, and the ratio of reaction substrates) were also evaluated and optimized using response surface methodology (RSM). Among IL tested, 1-butylsulfonic-3-methylimidazolium trifluoromethanesulfonate showed the highest catalytic efficiency for the esterification. Reaction variables were optimized using RSM as follows: IL load 4 % (relative to the weight of RA), molar ratio of methanol to RA 9.2:1, 67 °C, and 28 min. Under the optimized conditions, the esterification degree of RA was 92.3 ± 1.7 %.

Highly Efficient Synthesis of Hydrophilic Phytosterol Derivatives Catalyzed by Ionic Liquid

“…The effects of different IL on the mass and molar conversion rates were investigated under the selected condition: 100 °C, 4% IL (w/w, related to the mass of both reactants), 1:1.5 molar ratio of PSHS to PEG 2000, 0.5 and 1 hour. Four Brønsted acidic IL, [BSO 3 HMim][HSO 4 ], [BSO 3 HMim]TS, [BSO 3 HMim]TA, and [BSO 3 HMim]Cl, were selected as potential catalysts according to previous studies (He et al, ; Sun & Li, ). As shown in Fig.…”

“…In this study, first, IL were used for the synthesis of hydrophilic phytosterol derivatives in solvent-free system. The effects of different IL on the mass and molar conversion rates were investigated under the selected condition: 100 C, 4% IL (w/w, related to the mass of both reactants), 1: Sun & Li, 2016). As shown in Fig.…”

“…In recent years, IL have gained more and more attention as either catalyst or solvent. Among all IL, Brønsted acidic IL displayed excellent catalytic activity for esterification or transesterification and have been extensively used for the synthesis of biodiesel (Ghiaci, Aghabarari, Habibollahi, & Gil, 2011;He, Liu, Yu, Si, & Zhang, 2016;Li, Hu, Cheng, & Lou, 2014;Sun & Li, 2016).…”

Synthesis of Ricinoleic Acid Estolides by the Esterification of Ricinoleic Acids Using Functional Acid Ionic Liquids as Catalysts

“…The AV of the estolide 56.9 2.9 mg KOH/g was lower than that reported previously 65 mg KOH/g 1 and reaction time 10 h was significant shorter than those 48 h of lipasecatalyzed reactions 1,7 . These results were attributed to the strong acidity of BSO 3 HMIM TS 21,22 , which can provide more catalytic activity sites for the esterification.…”

Synthesis, Analysis and Thermoelectrochemical Applications of Ionic Liquids

“…Brand BF4 -anions[79].Lethesh, et al showed that nitrile functionalized ILs with thermal stability, especially triflate and trifluoro acetate anion containing ILs, are promising solvents for the dissolution of biomass[80]. six different functional ILs as received by Sun, et al[82]. Fu, et al designed alkoxysilyl-functionalized ionic liquid by ultrasonic/microwave synergistic method…”